1. Field of the Invention
The present invention relates to a frequency error estimator, which calculates a frequency error between a transmitter and a receiver of a mobile communication system that uses a reference code and can thus achieve high estimation precision while reflecting variations in frequency over time, and an operating method of the frequency error estimator.
The present invention is based on research (Project No.: 2006-S-001-02, Project Title: Development of Adaptive Wireless Access and Transmission Technology for Fourth Generation Mobile communication) conducted as part of Information Technology (IT) Growth Power Technology Development Project launched by Ministry of Information and Communication and Institute for Information Technology Advancement (IITA).
2. Description of the Related Art
In general, a receiver in a mobile communication system uses a synchronous detection method to obtain excellent detection.
A mobile communication system using the synchronous detection method reproduces a carrier wave that is synchronized with the carrier frequency of an input signal, and detects symbols based on the reproduced carrier wave.
However, a frequency error is highly likely to occur between a transmitter and a receiver of a mobile communication system due to the difference between the precision of a local oscillator of the transmitter and the precision of a local oscillator of the receiver and carrier frequency variations caused by temperature variations.
A frequency error between a transmitter and a receiver of a mobile communication system may alter the phase of an input signal and may thus deteriorate the performance of the mobile communication system.
Therefore, it is necessary to develop a frequency error estimator capable of improving the performance of a mobile communication system by compensating for a frequency error so as to realize synchronous properties for a receiver.